1. Field of the Invention
The present invention concerns a method for filtering a suspension of particles in a liquid and a device for implementing this method.
2. Description of the prior art
The method is of the type in which:
the liquid of the suspension disposed on a first side of a porous membrane is passed continuously through the membrane so as to obtain a flow of filtered liquid on the second side of the membrane, particles from the suspension then collecting in an undesirable manner on the first side of the membrane and clogging its pores,
and the filtered liquid is caused to flow at least momentarily in the opposite direction to the aforementioned flow towards the membrane so as to return to the suspension the particles collected on the first side of the membrane during the aforementioned passage of the liquid therethrough.
The device is of the type comprising:
a porous membrane the pores of which are adapted to hold back the particles, the suspension being disposed on and in contact with a first side of the membrane,
means for passing the liquid of the suspension through the membrane from the first side of the second side so as to obtain a flow of filtered liquid on the second side of the membrane, particles then collecting in an undesirable manner on the first side of the membrane and clogging its pores, and
means for exerting on the second side of the membrane a momentary pressure such as to cause the filtered liquid to flow in the opposite direction to the flow so as to return to the suspension the particles collected on the first side of the membrane
A method and a device of the types indicated hereinabove are described in French patent application No. 2.513.536. In this patent application the system for causing the reverse flow of the filtered liquid comprises a piston movable within a cylinder communicating with the filtered liquid that has passed through the membrane and means for controlling the movement of the piston.
This device has a disadvantage. The reverse flow system requires an obstacle to the flow of the filtered liquid, such as a valve, so as to interrupt the flow of the liquid during the reverse flow. This reduces the reliability of the device.
A specific object of the present invention is to alleviate this disadvantage.